This is not surprising in lots of ways. I broke up with my partner of 4 years last week. No kids, didn't live together at that moment in time, it was an "easy" breakup. I'm even the one who instigated it!
We had various communication/priority/time issues anyway but our futures didn't line up together and I realised I didn't want to follow his path (dictated by his career).
I don't think it was the wrong decision. I'm just really sad all of a sudden. I was fine for a few days and I think I'm now grieving - everything is a reminder of buying it together/living together with X in the room as well, etc.
I don't necessarily miss him but I miss it and what I thought it could all be.
I'm young and I have time and we weren't married and I know this is so minor in comparison to lots of others here. But...I'm just sad.